DIFFERENCES IN THE RESPONSES OF 2 MUDSKIPPERS TO TERRESTRIAL EXPOSURE

The concentration of NH4+ in the plasma and muscles of Periophthalmodo n schlosseri and Boleophthalmus boddaerti increased significantly afte r exposure to terrestrial conditions for 24 hr. Such increases in NH4 concentrations in B. boddaerti were not accompanied by any significan t increase in urea concentrations. However, significant increases in u rea concentrations occurred in the plasma, liver and muscle of P. schl osseri kept away from water. Results obtained indicate that the liver may be a major organ involved in urea production in this mudskipper. I n addition, there were significant increases in the concentrations of total free amino acids in the plasma, liver and muscle of P. schlosser i, but not in those of B. boddaerti, after 24 hr of terrestrial exposu re. Terrestrial exposure also affected the aminating and deaminating a ctivities of glutamate dehydrogenase from the liver of P. schlosseri, leading to a significant increase in the aminating/deaminating ratio. It is concluded that P. schlosseri, having developed a greater affinit y to land than B. boddaerti, has also acquired a greater capacity to d etoxify ammonia.